The present invention relates to a sealed housing for an electronic device having a housing bottom part which has a first contact surface, a housing top part which has a second contact surface, the housing bottom part being connectable to the housing top part; and a seal which can be placed between the housing bottom part and the housing top part in such a way that it contacts the first contact surface and the second contact surface to form a seal when the housing bottom part and housing top part are joined together. The present invention also relates to a respective seal.
Although it can also be applied to any desired sealed electronic housing, the present invention as well as the problems on which it is based are explained here with respect to a sealed electronic housing onboard an automobile.
FIG. 2 shows a schematic cross-sectional diagram of a known sealed electronic housing.
FIG. 2 shows a pan-shaped housing bottom part 1a accommodating a circuit board 3 having an electronic circuit, circuit board 3 being secured by mounting pins 2 in a known manner.
Housing bottom part 1a has an upper peripheral edge 10 which provides a sealing surface for a sealing ring 3.
A housing top part 1b in the form of a cover having a second contact surface 11 on which sealing ring 3 may be placed is mountable on housing bottom part 1a. Cover 1b is rounded at the edge and contacts housing bottom part 1a at its ends. At this point, it is possible for housing top part 1b to be clamped to housing bottom part 1a, as is also known in the related art.
With such a known, two-part, sealed electronic housing, sealing ring 3 is used to protect the electronic circuit provided on circuit board 3 from environmental influences such as moisture. Seal 3 is usually designed as a sealing cord or packing ring and may be manufactured of silicone by the injection molding method, for example, and may be integrally molded on housing bottom part 1a and housing top part 1b. 
In the case of an integrally molded sealing ring 3 such as that illustrated in FIG. 2, base 3a connected to second contact surface 11 is advantageously designed to be wide, but tip 3b which is connected to first contact surface 10 is designed to narrow. This yields a strong adhesion at base 3a (in the case of a seal 3, which is integrally molded on housing top part 1b and forms a seal with housing top part 1b, and a seal 3, which is integrally molded on housing bottom part 1a and forms a seal with housing bottom part 1a) and at the same time a high surface pressure is achieved on the opposite contact surface.
One disadvantage of the known sealing ring 3 has been found to be that undermigration may occur under certain environmental conditions. For example, it is known that silicone seals may show undermigration on zinc surfaces when exposed to salt fog. The silicone seal therefore loses its adhesion at the base. Since the base is shaped to be wider, this yields a lower surface pressure and therefore the electronic housing may become leaky.
The sealed electronic housing according to the present invention and the corresponding seal have the advantage over the related art that it is possible to prevent undermigration while at the same time minimizing the additional sealing material used.
Due to the design of the seal according to the present invention as a disk instead of a packing cord, the influence of adhesion of the seal on the contact surface of the base carrier can be minimized. If such a sealing disk becomes detached from the base carrier, the sealing effect is still provided by the disk itself and thus the imperviousness of the electronic housing is guaranteed even in the event of undermigration.
Thus, an idea on which the present invention is based is that the seal, which is insertable between the housing bottom part and the housing top part in such a way that it contacts the first contact surface and the second contact surface when the housing bottom part and the housing top part are joined, is in the form of a continuous disk.
According to a preferred refinement of the present invention, the seal has an essentially planar back side which contacts the second contact surface over the entire surface area.
According to another preferred refinement, the seal has a peripheral integrally molded bulge on the front side, the tip of this bulge contacting the first contact surface.
According to another preferred refinement, the housing bottom part has a pan-shaped design and the first contact surface is provided on a peripheral edge.
According to another preferred refinement, the housing top part is designed in the form of a cover, and the second contact surface is provided on the inside of the cover.
According to another preferred refinement, the first contact surface is designed in the form of a bezel.
According to another preferred refinement, the seal is designed in one piece with the housing top part.
According to another preferred refinement, the seal is integrally molded or cast onto the housing top part.